Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 182021

321 PM CDT Sat Oct 18 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 318 PM CDT Sat Oct 18 2014


Main concern is the potential for some patchy frost tonight.  Low
clouds were found across the northern and eastern parts of the CWA
this afternoon.  Expect these clouds to clear out early this evening
as with the loss of daytime heating at the same time drier begins to
move into the area from the north.  Temperatures have not climbed as
high as they otherwise could have where the clouds have been today.
However there has also not been much mixing in these areas either
which did not lower the dewpoints.  Still think that we should see
some of the lower dewpoints currently over Iowa advect into the area
tonight.  Skies will clear this evening and winds will turn light as
surface ridge moves across the area.  Have lowered temperatures a
degree or two below MOS guidance where the surface ridge will be at
12Z.  Have also added some patchy frost given the expected mid 30
lows, light winds and clear skies.


.LONG TERM:  (Sunday through Next Saturday)
Issued at 318 PM CDT Sat Oct 18 2014

(Sunday through Tuesday)

Still expect this to be mainly a dry forecast except for Sunday
night and Monday when a passing upper trough and attendant cold
front will bring a chance for isolated/scattered showers.  Still
have best chances from the St. Louis east and south based on the
consistent GFS/ECWMF solutions.  Do not expect as many clouds
tomorrow with highs in the 60s.  Temperatures by Monday will finally
return to the upper 60s and lower 70s.

(Wednesday through Saturday)

Expect continued dry weather during this period.  Both the ECMWF and
the GFS have an upper ridge over Missouri and Illinois as an upper
low sinks southeastward from the central Rockies into Texas.
Meanwhile the large east coast upper low will lift northeastward.
This pattern favors subsidence over our area.  Temperatures will be
close to seasonal normals with forecast soundings showing mixing
only to 900mb with temperatures in the 10-15C range at this level
through the period.



.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 109 PM CDT Sat Oct 18 2014

Scattered to broken clouds between 2.5Kft and 3.5Kft will continue
to move southward mainly over Illinois and parts of the eastern
third of Missouri. These clouds are in response to low-level
moisture moving southward between surface high from southern
Minnesota through eastern Nebraska and low center northeast of the
eastern Great Lakes region. Suraace winds of 10 kts with local
gusts of 15 kts can be expected this afternoon over eastern
Missouri and much of Illinois. As the surface high moves southeast
skies will clear this evening over the region.

Specifics for KSTL: Low level moisture from the north continues to
move southward over eastern Missouri and much of Illinois
resulting in scattered to broken layers of clouds. Surface winds
from the north-northwest of 10kts with gusts to 16kts will
diminish this evening. Skies will become mostly clear after
02-0300 UTC period.





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